Construction work on the Tribeca section of the Hudson River Park began to heat up this holiday season. The three-year, $70 million project will include two sturdier and longer piers, more elaborate play areas and many of the uses that used to be on Piers 25 and 26. Above, at N. Moore St. the Downtown Boathouse building being demolished on Pier 26, which also housed the River Project marine study center. Below, a new tent the Trapeze School of New York will use during the cold weather until it moves to its new location at Pier 40 this coming spring or summer. Chris Martin, a spokesperson for the Hudson River Park Trust, the state-city authority building and managing the 5-mile-long park, said the temporary tent received the approval of Community Board 1.